Glower for electrical incandescent lamps.



0. M. THOWLESS. GLOWBR r011 ELECTRICAL INGANDESGENT LAMPS. APPLICATION FILED JAN.20, 1911.

1,123,625, Patented Jan. 5, 1915.

UNITED STATES PATENT OFFICE- ORLANDO M. THOWLESS, OI NEWARK, NEW'J'ERSEY.,

GLOWER FOR ELECTRICAL INCANDESCENT LAMPS.

Specification of Letters Patent.

Application filed January 20, 1911. Serial No. 603,668.

although tubes, rods or other forms may be made for the purpose, the said glowers be- 1Il,'Z made from finely powdered materials 15 and when finished shall be conductive-and luminous under the-action of a suitable electric current. I

The object of this invention is to produc glowers' which shall be more regular and even in their light-emitting qualitiesthan those at present in use and be stronger and well ada ted for commercial purposes.

One form of this invent on consists in basic filaments made from refractory metals such as tungsten. titanium or molybdenum, all of which I have used for basic filaments and on these I have deposited tungsten in some cases and titanium'in others.

Another form consists in filaments having a high specific resistance as compared with solid metal filaments, so that shorter and thicker glowers may be used than those made entirely of metal, and on this form of filament a coating of refractory metal is deposited of the same nature of one or more metals such as disclosed for the first form above mentioned. In this form the powders forming the filament can be so changed and arranged as to enable the maker to control and lan any resistance for them at a givenlength and cross-section. this being accomplished by adding a varying quantity of refractory resistance material to the metal powders hereinbefore mentioned. The refractorv resistance material I have used for the above purpose is oxid of thorium, zirconium. yttrium. magnesiumvor aluminum.

In regard to the plan of controlling the resistance it should be understood that where metallic powderand oxid for instance) are mixed together and made into filaments. the larger the amount of oxid added to agiren amount of metal powder the -higher will be the resistance and this can be increased to any degree by the additlon of more of the oxid powder for, the same dimensions of the glower.

As an illustration of my mvention and a) show how it is carried into effect I will give here one form of refractory metal powder, also one form of resistance material with one of refractory metal, with the methods of making the same into filaments. For example, tungsten in fine powder and in a high degree of purity is intimatel mixed with a b nding material and formed into a paste. This b nding material may be such as paraffin. The paste is then squirted through a small hole in a die, under proper pressure, 1nt0 filamentar form, having a thread-like appearance. This is cut into lengths and shaped into filaments proper for lamps.-

These filamentsare then placed in an oven wherein the temperature is gradually raised until all the araflin is driven out and is dissi ated. They are given a heat suilicient to ,frit the metal particles together and Patented Jan. 5, 1915. y

when cooled are mo nted between terminals under a bell-iar and after the bell-'jar has been exhausted of air a coating of refractungsten, such as the pentachlorid, WC], or

the hexachlorid, WCI is prepared and '80 tory metal is given to them. This may be placed in a receptacle connected with the bell-jar and heated to a vaporizing temperature. A filament'is placed in the bellar and connected with electrical terminals, thebell-ja'r'is exhausted of air, the vapor of tungsten salt is mixed with the pure dry' hydrogen or other reducing gas and the" mixed vapors are allowed to enter the bel' iar. A proper current, sufficient to raise the filament to a temperature high enough to cause the varors to. decompose. ism'ade totraverse the filament which results in a deposit of tungsten upon the filament. lule it may bebetteniin most cases, to deposit the should be made after the filaments have received the high fritting temperature. In-

all cases it will be found that if a very high temperature is given to the filaments, after the binding substance has been removed, a

filamentof closer grain will be obtained. The high temperature may be given by means of an electric current in 'vacuo or in powder with a solution of an atmosphere of inert gas.

In the foregoing example a glower is described made of metal only. For the higher resistance the mode of procedure is as follows: Metal powder, such as tungsten, is intimately mixed with a powder such as oxid of zirconium, aluminum or other oxid and this mixture is formed into a paste with a binding substance such as paraffin. The paste is then forced through a fine hole into a filamentary form, having a thread-like appearance. This is cut into proper lengths and shaped into filaments suitable forlamps. The binding substance is eliminated by heat and a high temperature is caused to act upon the filaments until all the particles are closely united together in a manner similar to fritting or welding. The filaments then receive a deposit of refractory metal to reduce their resistance to commercial requirements and to make the filament uniform in its light- 7 giving qualities.

Another method of making the high resistance filament is to form a paste of metal a salt which, under the action of heat, will become changed to an oxid. For instance, nitrate of aluminum dissolved in water and somewhat concentrated will form a jelly-like mass. This is mixed with the metalpowder and, in this .condition, serves as a binding substance.

The mass is then forced through a die-hole, formed into filaments and the nitrate of aluminum changed into oxid of aluminum by means of heat. This may be performed in a bell-jar under the action of an exhaust pump while the filament is raised to a high temperature by means of an electric current. The filament may then be coated with the refractory metal in the manner previously set forth.

In some cases itwill be desirable to form the basic filament of a ductile metal such as tantalum, molybdenum and the like even if the methods of forming such metals into' ductile wires may be expensive. Also. tungsten may be drawn into wire by working it at a rather high temperature, therefore it is contemplated in this invention to 'make such wire and while it is in a heated condition to shape it into the formvdesired and then deposit a coating of refractory metal thereon. iolybdenum. tantalum and other wires may be made into filaments and covered with vapor of hexachlorid of tungsten or other metal, as a coating of this nature equalizes the surfaces and protects metals which have a low vapor density.

I show in the accompanying drawing an enlarged view of a portion of the finished filament, a part of which is shown broken away to display its construction. In this drawing the coating is represented as A, and the basic filament as B.

Having thus described my invention I claim in raising metal filaments to a temperature above the softening point of platinum,

bringing vthem while in such heated condition into close contact with mixed vapors of hexachlorid of tungsten and dry hydro en and causing a resistance equalizing flashing of tungsten to form on the filaments.

3. In the manufacture of glowers for electrical incandescent lamps the steps which consist in vaporizing hexachlorid of tungsten, mixin itwith dry hydrogen, admitting the nnxture into an exhausted vessel containing a refractory metal filament connected with electrical terminals and raising the filament to a high temperature to the extent that it receives a resistance equalizing flashing of tungsten.

4. In the manufacture of glowersfor electrical incandescent lamps the steps whichconsist in vaporizing hexachlorid of tungsten, mixin the vapor with dry hydrogen and admitting the mixture into an air-exha'usted vessel containing a refractory metal filament raised to a high temperature.

5. In the manufacture of glowers for .electrical incandescent lampsthe steps which consist in raising filaments to a high temperature in an atmosphere composed of the tungsten and dry hydrogen, decomposing the mixed vapors and depositing a coating of tungsten on the heated filaments.

6. In the manufacture of glowers for elec the filaments a flashing of tungsten.

7. In the manufacture of glowers for elecrical incandescent lamps the steps which onsist in subjecting filaments to an elevated emperature in an atmosphere composed of nixed vapor of hexachlorid of tungsten and lry hydrogen and depositing on them a :oating of tungsten. I

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.-

ORLANDO M. THOWLESS.-

' Witnesses:

ARTHUR J. Tnownnss, HERBERT L. Tnowmssg 

